IAF Magazine Articles

Delilah's Secrets

This is the story of the Delilah, a sophisticated cruise missile developed in the State of Israel. For many years the Delilah was highly classified, one of the IDF's biggest secrets. Now, she reveals her secrets in the IAF Magazine.

Noam Ofir and Or Yaakov | Photography: Israel Military Industries

In the mid-eighties Israel Military Industries (IMI) revealed a new kind of weapon that had been a long time in the making: a UAV (unmanned aerial vehicle) that was intended for launch from combat aircraft, rather than from the ground. It gave it the biblical name Delilah.

The new UAV's mission was also original. Unlike other UAVs that appeared at that time, most of which were manufactured in Israel, the Delilah was not intended to carry a camera and collect information on enemy troop moments. It was also not intended to return home when it had completed it's mission, it lacks a landing gear or skis. According to official publications, the aim of the Delilah was deception, to draw enemy anti-aircraft fire and thus clear the path for manned combat planes. The logic was clear: It's preferable to loose a Delilah UAV than to loose a combat craft and its crew.

However, after the Delilah was introduced 25 years ago, it did not seem like a success story. Its 'younger brother', IMI's "Samson" missile, was purchased in large quantities by the US Navy. Many improved versions of the "Samson" were also released, and the Delilah disappeared almost entirely. Closer to home, the "Samson" was used extensively in 1982 during Operation "Mole Cricket 19", in which the IAF successfully attacked and destroyed Syrian antiaircraft (AA) systems in Lebanon's Beqaa valley. The Delilah stayed out of the picture.

For years, foreign military journals who had followed the Delilah closely when it was first introduced by IMI hardly mentioned it at all. When they did mention it, it was in the context of the successful "Samson" system. The message was clear: the "Samson" was a success story, the Delilah was not.

However, in truth the disappearance of the Delilah was not an indication of failure, but rather a product of its success. Behind the scenes, far from the eyes of the media, the Delilah became one of the most advanced and sophisticated weapons systems developed in Israel. The UAV, initially presented as a vehicle for deception, successfully completed its mission. It did not deceive enemy antiaircraft systems, but did mislead everyone who was not in on the project's real secret. Today, we can reveal that the Delilah was never truly intended to serve simply as a decoy.

The fascinating story of the Delilah, revealed here for the first time, is the story of an idea born in the Israeli Air Force during the difficult period after the Yom Kippur War. An idea that, despite its ups and downs, resulted in an advanced cruise missile whose capabilities and performance may well be unmatched by any other weapons system. Some parts of the story remain classified to this day, but the details that we can reveal are enough to convince anyone, even if they aren't missile experts, that the Delilah is one of the most important weapons in the IDF's arsenal.

Turning Over Every Stone

As has been mentioned, the roots of the Delilah project are found in the second half of the seventies, in the days following the Yom Kippur War. During the war and the War of Attrition that followed, the Air Force felt the difficulty of coping against modern antiaircraft systems to its core. Despite the great efforts put into it, including new weapons systems and modus operandi, the Air Force continued to suffer difficult losses when it attempted to neutralize Egyptian and Syrian antiaircraft systems. As a result, it had to operate in a well-defended area. The result was many IAF aircraft brought down, and more than a few crews killed or taken prisoner. General Ezer Weizman put it best, in the expression that became famous: "The missile bent the plane's wing".

After the war, the IAF began a comprehensive project to find an answer to enemy AA capabilities. From the start, it was clear to everyone involved that there was no easy solution. There was no single method or small change in combat doctrine that would prevent the difficult outcomes of 1973 from returning if war with the Egyptians or Syrians resumed. The answer would need to include a mixture of new attack methods, including weapons, intelligence systems, command and control and combat doctrine. In short, what was required was comprehensive changes to the way that the IAF functioned and fought.

Other large organizations are afraid of change, but the Air Force understood that this was a change it needed to go through. The result was one of the largest projects the Air Force has ever undertaken. Sums that were huge then, and that would also be considered huge today, were invested in finding ways to cope with the AA threat. In addition to bearing the steep financial cost, the Air Force expressed willingness to examine any idea that could help solve the problem. The result was that during the second half of the seventies it tried out countless ideas, some of which seem ludicrous today, as part of its struggle to "turn over every stone" to find a solution. We should note that during that period the US also lacked a good solution to enemy AA equipment, and that they followed the Israeli efforts closely.

Decoy

As part of the search for a solution to enemy antiaircraft capabilities, the idea of developing a missile to act as a decoy was raised. The idea was not particularly original as the Americans had already developed missiles and UAVs that mislead AA systems by overloading their radar systems. The plan was simple: AA systems scanned the skies using radar to hunt for enemy aircraft. On detecting an aircraft they locked on to it, targeting it with missiles and their cannons. But what would happen if the enemy craft was a UAV? In this situation the AA system focused its radar on the UAV, allowing the manned fighter planes to approach in relative safety.

In order to fool the enemy, it was important that the decoy UAV would "appear" like a manned aircraft, not in the sense of how it looked, but rather how it would appear on the enemy's radar systems. Thus, the important factor was its flight profile, the speed and height of its flight. A UAV that did not fly in a path appropriate for a combat plane, for example by flying too slowly, would be identified as a decoy, and fail to draw the enemy's attention. Similarly, a UAV whose radar echo was too large or too small would also be identified as a decoy.

"During 1978 a small group in the aeronautic planning branch of the Air Force's equipment group were instructed to develop the decoy missile", recalls Moshe Sharoni, a former head of guided weaponry at one of IMI's factories. "The team, which started as group of five or six people, must have reached each peak with around 25 participants. The aim was to develop a missile that was launched from the ground and that could be used to fool enemy radar".

The project, nicknamed "High Heart", was a cruise missile with a jet engine that could mimic the characteristics of a fighter plane. "High Heart" was intended to be launched from the ground using a booster rocket that separated after the launch. After separation the missile's jet engine would kick in and carry it into enemy territory.

The "High Heart" project achieved technological maturity, explains Sharoni. "We launched a few prototypes of the missiles, including trials which demonstrated the rocket assisted launch, the separation of the booster and the missile itself, the activation of the jet engine and its continued flight".

However, despite the successful trials, two changes took place that brought about the premature termination of the project. First, the IAF realized that there was little logic in developing and manufacturing missiles itself. Though the IAF sets out the requirements of the systems, and will go on to receive and operate them, this does not mean that it must invest its human and financial resources in developing them itself. The "High Heart" is another example of a project internal to the Air Force that swelled to large proportions, before the decision was taken to transfer it to one of the companies in the defense industry.

The more significant change, however, was in the Air Force's operational thinking. In parallel to developing means to fool enemy AA systems, the Air Force invested in developing systems to attack them directly. As one of the IAF Commanders in Chief once put it: "The best electronic warfare is a one ton bomb". Rather than making do with fooling enemy AA systems, why not simply try and destroy them? It was here that the idea of "Stand Off" entered the picture.

Attacking the Battery

Like every weapons system, the AA system has a limited range. This range varies between a few kilometers and tens or even hundreds of kilometers. It's also important to distinguish between the maximum range the system's radar can detect a threat, and the maximum range over which is can launch its missiles, which is generally shorter. If you want to ensure that a plane survives, you need to keep it out of the AA's kill zone. In other words you should make sure that it can launch its weapons whilst it is still out of the enemy's range. In order to do this, you need longer range weapons than the enemy has, which can be guided from afar.

There are various ways to guide a weapon against an AA target. One popular method is to home in on the radar emissions given off by the AA system. The main problem with this method is that the enemy is wise to it, so many systems do not transmit continually, but only when they open fire. The early generations of radar emission-based homing missile had trouble adapting to AA systems that suddenly stop transmitting. They would approach the transmitting target, which would suddenly be switched off. As a result, on more than one occasion, the missiles missed their targets.

One of the solutions that was adopted was using electro-optic weaponry, with 'televisional guidance'. The missiles would transmit the images from an onboard camera, which would be used to navigate it remotely and allowed for very precise targeting. Though it did not rely on enemy radar emissions, this system also had its disadvantages.

Developing an Answer

Whilst trying to find a solution to the problem posed by enemy AA systems, the IAF equipped itself with different types of bombs and missiles. Some were purchased in the US, but a good number were developed in Israel.

The switch to relying on striking enemy AA systems reduced the importance of the "High Heart" project. "Our first thought was that it would be best simply to shut the project down", explained Sharoni. "But very quickly we understood that it would be a waste to abandon the unique development work that had already been done to create a decoy missile. Thus, as well as turning to the various arms manufacturers, we tried to come up with ways to leverage the knowledge and technology we'd already developed. Then came the best idea: why not take the decoy UAV we'd already developed, adjust it for launch from the air instead of from the ground, remove the parts intended to mislead the AA radar, equip it with a small warhead and use it to attack AA batteries from a distance of hundreds of kilometers?" Thus began the first stage of converting the "High Heart" from a decoy missile to an attack cruise missile.

A number of arms manufacturers examined the possibility of turning the idea of an anti-AA cruise missile into reality. In the end IMI took on the project, but not before many other manufacturers had turned it down. It's important to remember that this was no trivial matter. "High Heart" was a ground-launched decoy missile whose development was never completed. IMI needed to take everything that had been learnt during this project and turn it into a televisually guided long range cruise missile that could be launched from standard combat planes.

A not insignificant part of the team IMI put together to develop the missile was made up of former IAF personnel. In fact, many of those who had worked on developing "High Heart" were taken on by IMI and put to work directly on the program. The transfer of the project to IMI also did not end the Air Force's involvement in the project. Like many other projects, the cruise missile program was managed with the complete participation of the IAF.

Go Around

In terms of its structure, the Delilah is almost identical to a typical air-to-ground missile. The front section includes the homing parts, which in the first models were televisional. Thus, the head of the missile includes an antenna for general guidance towards its target. The next section holds the various electronic parts including guidance systems and flight control. The part behind this holds the warhead and fuel supply. The final section is made up of a jet engine capable of producing 165 pounds of thrust and the control surfaces that turn the missile towards its target.

Examining the technical data alone raises the question of why the Delilah is considered such an important missile. After all, there are missiles capable of flying further and faster and carrying warheads many times larger which are available on the global weapons market. The answer lies in the fact that the Delilah is seen more as a "loitering missile" than a cruise missile.

In general typical air-to-ground missiles are launched in the general direction of their target. A navigational system (such as GPS) takes them to the spot where intelligence indicates that the target lies. If the missile is autonomous ("fire and forget") then the plane that launched it can simply leave. The missile flies towards the target. When it identifies it, it strikes it with the help of its final guidance system. When the target is not where it is expected to be, the missile is simply written off. An example of this sort of weapon is the US Tomahawk missile, at least in its early models.

When a missile is fitted with an electro-optic guidance system, it broadcasts an image of what is in front of it, back to the aircraft that launched it. The image from the homing device is shown on a special screen in the cockpit, usually facing the navigator’s chair in a two-seater aircraft. The navigator can send the missile instructions, and make small changes in its flight path. However, these changes can only take pace during a relatively short period of time, and are comparatively minor. From the moment that the missile begins its final approach, no changes can be made. The result is that although he has some control, the navigator is actually very limited. If a missile approaches a target, which at the last minute turns out to be moving, or the wrong target altogether, then the missile misses. Thus, there have been many events like the one in Yugoslavia in 1999 when an electro-optic bomb launched from a US combat airplane was launched at a bridge. Seconds before impact, a passenger train reached the bridge and all the navigator could do was watch in horror, knowing that many civilians would be killed. It is here that the Delilah's unique ability enters the picture.

Come and Go

The Delilah's operation is similar to what is described above; it, too, possesses a "Man in the Loop" mechanism, where the navigator controls the final direction of the missile. However, in the case of the Delilah there's a key difference: as the missile makes the final approach, if the target has moved or if there's a need to cancel the attack (for example, if civilians are spotted near the target), all the navigator needs to do is press a button in the cockpit which instructs the missile to abort its approach and return to linger. Thus, situations in which a missile is wasted on a target that has disappeared, or in which civilians are accidentally killed can be prevented. In the same way the use of a missile on a target that has already been destroyed can be prevented, saving valuable ammunition.

This is not the only value in the Delilah missile's ability to linger. One can imagine a situation in which the target's precise location is not known with any certainty, for example if it is a portable anti-aircraft launcher or land-land missile launcher. In this case the Delilah can be launched in the general direction of the target, based on intelligence reports. The missile would fly in the direction of the target, all the while surveying the territory with its homing equipment. The image appears in the cockpit, the Delilah serving effectively as a homing UAV. The Delilah patrols above the territory searching for its target. The missile’s long range can be exchanged for a prolonged stay in the air above the target. When the navigator identifies the target, or what is thought to be the target, he instructs the missile to fly towards it. If he has identified it correctly then the missile is directed to attack it. If he has not found the target then the missile is instructed to abort its approach and return to searching.

The Delilah missile's ability to both loiter and carry out repeated passes makes it the ideal weapon for attacking mobile sites like rocket launches. Everyone recalls the difficulty the US Air Force faced during the 1992 Gulf War when it attempted to locate and destroy the Iraqi "Al-Hussein" rocket launcher that was used to fire at Israel and Saudi Arabia. The Americans knew roughly where the rockets were being launched from but had difficulty locating the launchers themselves. As a result fighter planes were sent for long patrols over western Iraq every night. On many occasions the Americans identified the point where the missile was launched from, but by the time a counter-strike had been arranged the missile launcher had left the scene. It's in these sorts of operational profile that the Delilah performs best, perhaps better than any other weapons system. In these cases the Delilah can be launched towards the area intelligence expects the missiles to be launched from. The Delilah will fly above the area and search for missile launchers. When a launcher is identified, it will be immediately struck by the missile. If it's discovered that the target has not been identified correctly, for example if it's a dummy launcher or another vehicle that looks like a launcher (such as a petrol tanker), the missile receives the instructions to end its approach and continue to search for the real target.

"The Delilah is a system that can strike very precisely at critical, sensitive points from a great distance", explains Brigadier General (reserve) Arieh Mizrachi, who was once CEO of IMI."If we want to attack a command bunker, for example, and we know where it is situated and exactly which window we need to hit then we can do it. We can always make another approach and place the missile exactly where we want it. The extreme precision of the missile makes it possible for us to paralyze the enemy by striking their critical point. For example, if we send the missile through a window of a division's control center, then no one will be left to give orders, and we'll have silenced the whole division. It's important to understand that the target does not need to be a large command center. The 'Delilah' lets us strike at the brain of the enemy, even if it's a small mobile target like a command armored personnel carrier. Similarly, we can strike at a ship's command center without needing to sink the whole ship. This holds true for many other kinds of target like airports, logistics centers and so on. The moment we identify the critical point, the Delilah lets us hit it".

One Size Fits All

The Delilah's first full trials, launched from one of the IAF's Phantoms, took place in the nineties. The planners came across a unique problem. How can a full-scale trial of a missile with a range of more than 250 kilometers take place in a small country like Israel? The fact that the only place the trail can be carried out without endangering population centers is the Negev Desert only adds to the problem.

"If you want to launch this kind of missile, and have it fly its full range, then, at least theoretically, you have to close half of the state", explains Sharoni. "What you do is choose a test area that is a few dozen kilometers by a few dozen kilometers in which the missile will fly without being a danger. During the trial, instead of flying in a straight line we squeezed the full range of the missile into this square, so that it flew a relatively large number of circuits inside the area before running out of fuel".

The trials proved that the Delilah could fulfill the operational requirements, and at the start of 1994 it began to enter operational service in the IAF.

Different generations of a weapon often receive different names. For example, the first two generations of Rafael's Shafrir air-to-air missile were known as the Shafrir 1 and 2, whereas the next three generations were known as the Python 3, 4 and 5. However, for Delilah missiles this is not the case. Primarily for security reasons, it was decided that all of the missiles in the Delilah family would have the same name, not even appended with a generation number. However, the Delilah which the Air Force received in the nineties is not the same that it receives today, despite the fact that their external appearance is almost identical. The differences between different models of the Delilah are in fact so fundamental that they can be seen as totally different kinds of missile, despite their shared name. Thus, IMI help the IAF distinguish between the different models by marking the production number. For example, the missiles marked "block 30", "block 40" and so on.

For obvious reasons we cannot go into the details of the differences between the various generations of Delilah missile, but we can say that they were adapted for delivery by different aircraft. Whilst the missile was originally fitted for launch by the Phantom, it has since also been fitted to, amongst others, the Super Phantom, the F-16C/D and the F-16I.

A Navigator's Dream

"The training needed to operate the Delilah lasts a few months, and because of its complex capabilities, not everyone successfully completes it", explains First Lieutenant A., an F-16D navigator in the "Scorpion" Squadron who is trained on the Delilah. "The training process is long, complex and challenging. You start with simple scenarios, hitting a large target in open space, and advance to small targets that are located in densely populated areas".

“Despite the intense cooperation between the pilot and the navigator, the fact remains that the missile is operated from the navigator's cockpit. In the first stage you launch the missile and it flies towards the target you've given it. Later in the flight, you take control of the missile and direct it wherever you want. If you need to, you can press a button and the missile will loiter. The role of the pilot is to tell me when I've reach the point where I need to tell the missile to fly, and I can no longer tell it to continue to loiter".

"Even though you are not physically in the same place as the missile, and in fact are far away, the whole time you feel that you are part of it. The fact that you can fly the missile wherever you want, whilst you yourself fly to an area that is not under threat, gives you safety".

The publicity material produced by arms manufacturers tend to exaggerate, describing their weapons systems as "the best of its kind in the world!", so you need to approach them with caution. Whoever wants good evidence of the capabilities of a weapons system should ask those who train on it and who would need to operate it in real combat situations. In the case of the Delilah, the complements paid to the missile from its users are greater than those that appear in the IMI promotional brochures.

"During Pilots Course you start on the Piper, transfer to the Fouga Magister and continue to the A-4 Skyhawk. Whichever plane you are flying, you can always say 'this aspect could have been done better'. This remains the case when you transfer to the F-16", explains First Lieutenant A. "But when you begin to fly the Delilah, you just can't say it. No matter how hard they try, there is just no way to make any aspect of this weapon better or smarter. It's simply perfect. It's a challenge that's a lot of fun to cope with. It's not without reason that the tile on the first slide you see on the Delilah training course is 'Every Navigator's Fantasy'. Honestly, it's the most amazing weapon in the Air Force today".

Seven Years without Ilan

Confrontation

Ground to air missile systems are one of the central challenges faced by combat aircraft operating in enemy territory. In order to practice handling this kind of threat the Air Force carried out a workshop. All the flights shared one common denominator: a clear and present danger.